Owing to the modernization and expansion of worldwide cities, the quantities of population and cars in cities increase and the demands for parking spaces rise gradually. To meet such demands, flat parking lots, parking towers, or on-street parking grids are built in most cities. Although this method satisfies the needs for parking spaces, due to the widespread parking lots or grids over a city, drivers always need to search for a void parking space aimlessly while parking. This is extremely inconvenient for them.
Accordingly, it is highly desired to have a novel parking space sensor for improving the drivers' convenience in finding void parking spaces and thus shortening the time required to find one.